In refrigerating apparatuses of this kind, because frost builds up in evaporators and obstructs heat transfer during cooling operation, defrosting operations are performed periodically. Known defrosting operations include: methods in which electric current is passed through an electric heater that is embedded in the evaporator; and methods in which high-temperature refrigerant that has just been discharged from the compressor is allowed to flow directly into frosted cooling air (hot gas bypass methods).
However, because the temperature inside the cold storage room rises during defrosting operations in which cooling capacity is not fully operational, it is desirable to complete defrosting in as short a time as possible.
Furthermore, if defrosting is performed by allowing high-temperature refrigerant that is discharged from the compressor to flow through to the evaporator, then the refrigerant is still at high pressure and in liquid form. This liquefied high-pressure refrigerant is decompressed at a pressure regulating valve, for example, and is vaporized by exchanging heat with a heat storing agent in a low-pressure heat exchange path before being sucked into the compressor. However, the refrigerant may not be completely vaporized, and there has been a risk that a portion may be sucked into the compressor while remaining in liquid form and damage the compressor.
In consideration of such conditions, conventional refrigerating apparatuses have been proposed that include: a refrigerant circuit that conveys refrigerant that has been discharged from the compressor under pressure sequentially to a condenser, a decompressing apparatus, and an evaporator, and is recycled to the compressor; and a defrosting circuit that performs defrosting of the evaporator by conveying refrigerant that has been discharged from the compressor under pressure directly to the evaporator, wherein a heat storing apparatus is disposed that places a pipeline between the compressor and the condenser in the refrigerating circuit and a pipeline between the compressor and the evaporator in the defrosting circuit in contact thermally by means of a heat storing agent, defrosting time being shortened by storing heat from the discharged refrigerant from the compressor in the heat storing apparatus while the refrigerating circuit is operating, and using the heat that has been stored in the heat storing apparatus while the defrosting circuit is operating (see Patent Literature 1, for example).
Refrigerating apparatuses have also been proposed that include: a compressor; a condenser; a throttling apparatus; an evaporator; and a heat storing tank that incorporates a lower-pressure heat exchange path, a higher-pressure heat exchange path, and a heat storing agent, wherein the lower-pressure heat exchange path is connected to the refrigerating circuit as a parallel circuit by a suction bypass pipe, and a suction accumulator is disposed on the suction bypass pipe downstream from the lower-pressure heat exchange path, and liquid refrigerant that has not vaporized completely within the lower-pressure heat exchange path is accumulated in the suction accumulator such that only gaseous refrigerant is allowed to be sucked into the compressor when performing defrosting (see Patent Literature 2, for example).    Patent Literature 1: Japanese Patent Laid-Open No. HEI 4-292761 (Gazette)    Patent Literature 2: Japanese Utility Model Laid-Open No. HEI 5-1966 (Gazette)
In conventional refrigerating apparatuses such as that described in Patent Literature 1, some problems have been that two heat exchanging portions, i.e., a heat exchanging portion for storing heat during cooling operation, and a heat exchanging portion for using the stored heat during defrosting operation, are required, increasing equipment costs, and that dedicated piping is also required to absorb stored heat into the hot gaseous refrigerant and convey it to the evaporator during defrosting operation, increasing construction costs. Furthermore, in conventional refrigerating apparatuses such as that described in Patent Literature 1, no consideration has been given to vaporizing the liquid refrigerant that remains in the refrigerant after defrosting.
In conventional refrigerating apparatuses such as that described in Patent Literature 2, because two heat exchanging portions are required, i.e., a heat exchanging portion for storing heat during cooling operation, and a heat exchanging portion for using the stored heat during defrosting operation and vaporizing the liquid refrigerant that remains in the refrigerant after defrosting, and a large-diameter on-off valve for switching the flow channel on the lower-pressure side is also required, one problem has been that equipment costs are increased.